When an image is transmitted to a service server from a client computer, an image to be transmitted is selected from a list of images on a display by starting image display programs. Subsequently, a destination service server is selected. The service content of the service server is inquired, and image information is obtained, which is limited by the service server and includes an image size. For example, when an image size of the selected image to be transmitted is larger than the maximum image size limited by the service server, the selected image is subjected to image processing so as to be smaller in size, and then, the image is transmitted to the service server. Thus, even when an image to be uploaded to a service server has an image specification unsuitable for image service of the service server, the image can be automatically transmitted to the service server.